Synthesis of slanted and quasi-slanted SAW transducers

摘要

This paper is devoted to the synthesis of interdigital transducers (IDTs) with variable electrode periodicity in the direction orthogonal to the SAW propagation, including straight electrodes (slanted or fan-shaped IDTs) and stepped electrodes (quasi-slanted IDTs). A polarity weighting of electrodes is the only tool for realization of high-frequency selectivity in fan-shaped (slanted) transducers. Quasi-slanted transducers (QST) offer additional opportunities: optimization of apertures, periods, and relative shifts of acoustic channels. Moreover, a discrete apodization gives an extra flexibility for QSTs in realization of desired frequency responses without increasing SAW diffraction sensitivity. Original synthesis algorithms have been developed for optimization of slanted and quasi-slanted IDTs in SAW filters with a wide range of characteristics.